Thank you Kurt, that is exactly the explanation I wanted.
Maybe... managing the emptiness is the data processing main business.
"All things in the cosmos arise from being.
Being arises from NULL"
(sql translation of lao-tzu).
Thanks again,
Vincent.
On Thu, 18 Dec 2003 17:26:49 -0600
Kurt Welgehausen <[EMAIL PROTECTED]> wrote:
> 'ap_db eval {select lineid from tbl_ent}' returns an empty
> tcl list, which is the correct result.
>
> 'ap_db eval {select max(lineid) from tbl_ent}' returns a
> tcl list of length 1. The single element of the list is
> the result of the aggregate function max; since max cannot
> compute a value, it returns NULL. Since tcl does not have
> a NULL or nil or None value, it uses the empty string to
> represent the SQL NULL.
>
> % set a [list] ;# Your first result
> % llength $a
> 0
> % set aa [list ""] ;# Your second result
> {}
> % llength $aa
> 1
>
> Regards
>
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